Brain disorders represent a major challenge for today's societies. Despite intensive research efforts, therapeutic interventions for most psychiatric and aging-related disorders have been of moderate success. Obtaining better insight into the normal development of the nervous system - in particular the underpinnings of funcitonal properties of specific neuronal cell types - might enable more targeted interventions in the future. The goal of this project is testing the hypothesis that alternative splicing is a central mechanism for the amplification of molecular diversity in neuronal cells and that it controls critical aspects of synaptic specificity. To this end, we proposed to implement novel mass-spectrometry and RNA sequencing methods to define molecular diversity of neuronal gene families in mouse neurons. Moreover, we sought to unravel the logic of neuronal receptor repertoires across cell populations and test the importance of cell type-specific alternative splicing programs for synapse specification.